Understanding and Recognition of Integrated Automation System of Substation
In recent years, with the improvement of the power grid operation level, dispatch centers at all levels require more information in order to grasp the operation of the power grid and substations in a timely manner, improve the controllability of the substations, and require more remote centralized control and operation. Anti-accident measures, etc., that is, the use of an unattended management model to improve labor productivity, reduce the possibility of human error, and improve the reliability of operation. On the other hand, the application of modern computer technology, communication technology and other advanced technical means has changed the mode of traditional secondary equipment. In order to simplify the system, share information, reduce cables, reduce floor space, and reduce cost, it has changed substations. The face of running. Based on the above reasons, substation automation has shifted from a "hot topic" to a practical stage. All relevant departments in the power industry have applied substation automation as a new technological innovation to the operation of power systems, and major professional manufacturers have also adopted substation automation. As a key development project, the development of the system is constantly perfected and improved, and correspondingly launched various characteristic integrated substation automation systems to meet the requirements of the power system.
Overseas research and development began in the early 1980s. So far, major power equipment companies have successively launched serialized products. Companies such as ABB, SIEMENS, HARRIS, etc., since the 1990s, most of the world’s newly built substations have adopted all-digital secondary equipment; correspondingly, they have adopted substation automation technology; China’s research and development on integrated substation automation has been compared to developed countries in the world. Late, but with the maturity and wide application of digital protection equipment, and the mature application of dispatch automation systems, substation automation systems have been accepted and used by power system users. However, there are roughly two principles in the use of power departments: one is medium Low-voltage substations use automation systems to better implement unattended operations and achieve the goal of reducing people and increasing efficiency; second, for the construction and design of high-voltage substations (220kV and above), advanced control methods are required to solve various problems. Professionals are technically dispersed and self-contained systems, repeated investment, and even affect the reliability of operation. And in the actual project, there are still the following main problems:
(1) Duplicate functions, manifested in the respective settings of transmitters used in metering, remote control and local monitoring systems, which increase the load of CT and PT, increase investment, and also cause The inconsistency of data measurement; one of the remote control device and the microcomputer monitoring system is controlled by the dispatching station, the other is to serve the local monitoring, without resource sharing, which increases the investment and creates complexity on the site, which affects the reliability of the system;
(2) The system lacks a systematic design and forms the system in a way of "patch together" functions, resulting in low performance indexes of the entire system, and some functions and system indexes cannot be realized.
(3) There is a lack of normative requirements for the engineering design of the integrated automation system of the substation, especially the communication protocol of each part of the system. If products from different manufacturers are involved, there will be more problems, which will lead to a long joint debugging time for each system. , It will bring great inconvenience to future maintenance and operation, and then affect the investment rate of substation automation system.
2. Functions that the integrated automation system of the substation should be able to achieve
2.1 Microcomputer protection: It is to protect all electrical equipment in the station, including line protection, transformer protection, bus protection, capacitor protection and automatic switching, low-frequency load reduction and other safety automatic devices. Various types of protection should have the following functions:
1). Fault record
2). Store multiple sets of fixed values
3). Display and local modification settings
4). Communicate with the monitoring system. Send fault information and action sequence according to the command of the monitoring system. Current setting value and self-diagnostic signal. Receive commands such as selection or modification of the fixed value of the monitoring system, and calibration of the clock. Communication should use standard protocols.
2.2 Data acquisition
includes status data, analog data and pulse data
1). State quantity collection
state quantity includes: circuit breaker state, isolating switch state, transformer tap signal and substation primary equipment alarm signal, etc. At present, most of these signals are input to the system by photoelectric isolation, and they can also be obtained through communication.
The protection action signal is obtained through communication via a serial port (RS-232 or RS485) or a computer local area network.
2). Analog quantity acquisition
The typical analog quantity collected by conventional substations includes: various busbar voltages, line voltages, currents and power values. Feeder current, voltage and power value, frequency, phase, etc. In addition, there are non-electricity collections such as transformer oil temperature and substation room temperature.
The accuracy of the analog quantity acquisition should be able to meet the needs of the SCADA system.
3). Pulse volume
The pulse quantity is mainly the output pulse of the pulse watt-hour meter, and it is also connected to the system in a photoelectric isolation method. The internal counter counts the number of pulses to realize electric energy measurement.
2.3 Event record and fault recorder and distance measurement The
event record should include the protection action sequence record and the switch trip record. Its SOE resolution is generally between 1~10ms to meet the requirements of different voltage levels for SOE.
The fault recorder of the substation can be realized in two ways as required. One is the centralized configuration of a dedicated fault recorder, which can communicate with the monitoring system. The other is the decentralized type, that is, the microcomputer protection device is used for recording and ranging calculation, and then the digitized waveform and ranging results are sent to the monitoring system for storage and analysis by the monitoring system.
2.4 Control and operation lockout The
operator can remotely operate the circuit breaker, isolating switch, transformer tap, and capacitor bank switching through the CRT screen. In order to prevent the inability to operate the controlled equipment when the system fails, manual direct tripping and closing means should be retained during system design. The operation lock should have the following contents:
1). Computer five-prevention and locking system
2). According to the real-time status information, the operation blocking function of the circuit breaker and the switch is automatically realized.
3). The operation outlet should have a simultaneous operation locking function
4). The operation outlet should have the function of tripping and closing and locking.
2.5 Synchronous detection and synchronous closing
This function can be realized in two ways, manual and automatic. It can be realized by independent synchronization equipment or by a computer protection software module.
2.6 Local control of voltage and reactive power Reactive
power and voltage control are generally realized by adjusting transformer taps, switching capacitor banks, reactor banks, and synchronously adjusting cameras. The operation mode can be manual or automatic, and manual operation can be controlled locally or remotely.
Reactive power control can be realized by special reactive power control equipment, or by the monitoring system based on the voltage measured by the protection device, reactive power and transformer tap signals through special software.
2.7 Data Processing and Recording
The formation and storage of historical data is the main content of data processing. It includes the upper-level dispatching center, the data required by the substation management and protection professions, mainly including:
1). Number of breaker actions
2). Cumulative number of cut-off capacity and the number of trip operations when the circuit breaker cuts off the fault
3). Time recording of active and reactive power of transmission line, active power, reactive power and bus voltage of transformer
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